The present invention relates to an improvement of the intake passage of carbureted internal combustion engines for suppressing faulty carburetion caused by acoustic vibrations in the motor.
It has been observed that the main defects in carburetion encountered at low speeds, such as speeds on the order of 1200 - 1300 RPM, with conventional carburetors result from the presence of acoustic vibrations at the height of the carburetor. Since the level of these vibrations are subject to trememdous variationn over this speed range, the carbon monoxide content of the exhaust gas varies between such limits that satisfactory engine operation is impossible to achieve, if established antipollution norms are to be observed.
This phenomenon may be explained by the fact that the air supply at the level of the carburetor may be considered as being the sum of a constent flow supply and an alternating one of acoustic origin, the frequency and amplitude of which are determined or affected by the engine speed. When this amplitude is greater than that of the constant flow and the phase of the alternating supply is such that it opposes that of the constant flow supply, a net reverse flow occurs with actual backflow of the air-fuel mixtures to the carburetor where it is further enriched, thus causing an irregularity in the supply of fuel and an increase in the pollution of the atmosphere being caused by the engine.